Numerical Simulation And Experimental Research Of Gas-water Spray Quenching Process Of 9SiCr Under Ordinary Pressure

In order to study the performance of mixture gas-water spray quenching under different initial pressure and proportion of gas and water. In this paper both numerical simulation and experimental research were used to study the quenching process of 9SiCr under different initial pressure and the proportion of gas and water.Gas-water spray quenching is a new quenching technology, spraying the mist on the components to quench by compressing gas. The cooperation of two kinds of medium makes the cooling ability range of gas-water spray quenching much bigger, between the gas and the mist.The researches and applications of traditional quenching,high-pressure gas quenching and gas-water spray quenching was compared in this paper. The main current researches were summarized including numerical simulation of quenching cooling process, the surface comprehensive heat transfer coefficient, temperature field, stress field and microstructure transformation during quenching.The curves of temperature which are dependent on time were determined by test. The quenching curves show that bigger initial pressure lead to quicker cooling, as the proportion of gas and water is equal. And if the initial pressures were equal, the temperature gradient of test-specimen would be increased by the proportion of gas and water.The heat exchange boundary conditions were deduced, and the key parameter surface heat transfer coefficient was reached, using the anti-heat transfer method. Meanwhile, the surface heat transfer coefficient during quenching process was simulated by the finite element software DEFORM. The results showed that surface comprehensive heat transfer coefficient has multiple extreme value point, and ignore the influence of quenching cracking on the maximum point, another extremum was found between the temperature of 200～300℃. Moreover, when the proportion of gas and water is equal, the bigger initial pressure is, the bigger surface heat transfer coefficient and variation will get. And if the initial pressure is the same, the bigger proportion would get bigger heat transfer coefficient and variation.In this thesis we utilized ANSYS to simulate the temperature field and stress field during quenching. We got the temperature distribution on particular moments and the maximum variance of temperature is about 300℃. The moment of maximum temperature gradient was simulated for the stress field and got a result of stress field and strain field at the moment of maximum temperature gradient. The maximum stress reached 700Mpa.